ABSTRACT
Hydrodenitrogenation (HDN) on molybdenum-containing catalysts has re ceived considerable attention during the past decades. The kinetics and mecha nisms have been investigated with single nitrogen-containing compounds in laboratory reactors. Mechanistically, the HDN of unsaturated nitrogen-con taining compounds proceeds as follows: first, hydrogenation of the nitrogencontaining ring takes place, followed by the breaking of secondary C-N bonds to give hydrocarbons and ammonia. Normally, ring hydrogenation is the rate determining step. Pyridine [1,2] and quinoline [3-5] were often selected to do this type of study. Sonnemans et al. [1] studied the kinetics of pyridine hydro genation over а СоМо/АЬОз catalyst under atmospheric pressure. They re ported that the Langmuir-Hinshelwood equation described the reaction well with adsorption of hydrogen and nitrogen bases on different sites. Recently, Massoth and his coworkers [5] studied the kinetics of indole hydrogenolysis at 350°C and 3.55 MPa total pressure over a sulfided СоМо/АЬОз catalyst. The reported that the rate of the first C-N bond-breaking step to o-ethylaniline depended on the square root of the H2S partial pressure and was inhibited by indole and dihydroindole. Ring hydrogenation reactions were similarly inhib ited, but only slightly affected by H2S. Kinetic analysis supported the concept that the Langmuir-Hinshelwood equation with different catalytic sites involved the C-N hydrogenolysis and ring hydrogenation reactions. Nagai et al. [6] stud ied the kinetics of acridine HDN on a reduced Мо/АЬОз catalyst and reported that the C-N hydrogenolysis of perhydroacridine in the HDN reaction could be described by a Langmuir-Hinshelwood type of equation with a competition term for hydrogen and perhydroacridine.
